A powerful interracial tide has transformed friendships, dates, cohabitations, marriages and adoptions in just one generation. If the wave continues to grow, it could sweep away racial stereotypes and categorizations, as well as the rationale behind affirmative action and other broad minority protections. It remains to be seen, however, whether higher levels of social integration, especially among Asians, are benefiting blacks, the least integrated of U.S. minorities. Data from the 2010 census will make that a lot clearer.

For now, the interracial trend – while evident everywhere – is hard to gauge because young adults and children are at its vanguard: children such as Heshima Sikkenga, 9, of Apple Valley, Minn., for whom race “is a minor point, like brown hair or blond hair,” as his father, Steve, put it.

But the wave is so far-reaching that the average American today, young or old, is 70 percent more likely than Americans were a generation ago to count a person of another race among his or her two or three best friends, according to an article in the current issue of American Sociological Review. The same percentage of applicants tells Match.com, a leading Internet dating service, that they’re willing to date someone of another race.

“If the right person comes in a Latino package, that’s just part of who that person is,” said Kristin Kelly, a spokeswoman for Match.com.

“I’m seeing a lot more interracial couples,” said Javier del Cid, a 32-year-old Washington bartender who has worked in restaurants for 18 years. “They’re not scared anymore. You see a Hispanic guy with a black girl, you don’t say, `Oh, my God!’ Only people raised before it was accepted say that.”

Del Cid should know: A Guatemalan, he dates mostly black women.

A raft of social research ratifies his view:

_ In 1992, 9 percent of 18- to 19-year-olds said they were dating someone of a different race. A decade later, the figure was 20 percent, according to a 2005 study by sociologists Grace Kao of the University of Pennsylvania and Kara Joyner of Cornell University.

_ In 1992, 9 percent of 20- to 29-year-old Americans were living with people of different races. A decade later, Kao and Joyner found, 16 percent were.

_ In 1985, when asked to describe confidants with whom they’d recently discussed an important concern, 9 percent of Americans named at least one person of a different race. These days, about 15 percent do, according to Lynn Smith-Lovin of Duke University and Miller McPherson of the University of Arizona at Tucson, co-authors of the American Sociological Review article.

_ In 1980, 1.3 percent of marriages in the United States were interracial, according to the census. By 2002, that had more than doubled, to a still minuscule 3 percent.

One big reason is that the white fraction of the U.S. population is shrinking. Four out of 5 people in America were white in 1980, and today 3 out of 4 are, mainly because of surges in Hispanic and Asian populations. People’s friendship networks are more racially mixed today whatever their races, Smith-Lovin said, “primarily because society is more diverse.”

At the same time, racial attitudes are softening. In 1990, two-thirds of Americans polled said they opposed having a close relation or family member marry a black person. That’s dropped to about one-third, according to Maria Krysan, a racial attitudes specialist at the University of Illinois at Chicago.

More integrated workplaces also have a lot to do with it, according to researchers. Steve Sikkenga, 54, a federal Justice Department official in Minneapolis, Minn., agreed.

“The white-collar workers were all white when I started working at Detroit Radiant Products in Warren, Michigan, in the `70s,” Sikkenga said. “There were some other races in the shop, but there was no commingling to speak of. Where I work now it’s a lot different and a lot better.”

For singles in their early 20s, living on their own and newly freed from the opinions of parents and college cliques, workplaces are hubs for interracial contacts. One consequence: Americans age 21.5 are the likeliest of all to be living with people of another race, according to researchers.

Young adults ages 22 through 25 also typically have the most sexual partners and the most breakups. But while interracial couples who live together often marry, their relationships disintegrate short of the altar more often than those of same-race couples do. According to Kao and Joyner, the marital batting average is .213 for same-race couples who live together in their 20s. For mixed race couples, it’s .127.

When you’re young, “you experiment,” said Justice King, 38, a black Washingtonian who’s dated interracially. “You maybe want to be exposed to somebody of another culture. But by the time you’re 30, you know what’s going on. You’re ready to choose, ready to get serious.”

If disproportionate numbers of interracial relationships tend to be passing fancies, they may not be harbingers of big social changes. Even so, Duke sociologist Smith-Lovin noted in an e-mail, interracial intimacies of all kinds matter because “having a positive, cooperative tie to a person in another racial group makes us less likely to stereotype that racial group. So increasing the proportion of the population that has such a tie should make us less prejudiced and less likely to discriminate against people who are not of our own race.”

Whom the world changes for depends largely on who marries whom, however, and interracial-marriage figures vary widely by race, according to Zhenchao Qian, a researcher at Ohio State University. About 2 percent of whites and 5 percent of blacks intermarried, Qian found in an analysis of 20- to 29-year-olds based on the 1990 census. For Hispanics, Qian found, the interracial marriage figure was 37 percent; for Asians, it’s 64 percent.

(The 2000 census offered Americans so many new racial options – 63 and a wildly popular category called “other” – that traditional racial tallies were early casualties of richer social integration.)

The more subtle distinctions of the 2000 census showed, for example, that Southeast Asians weren’t matching the economic and educational performances of Chinese, Koreans or Japanese; Cubans did better than other Latinos; and black immigrants outperformed blacks born in the United States. So do they deserve equal protection and preference? John Skrentny, a University of California-San Diego sociologist who specializes in affirmative action, doubts it.

“Affirmative action categories were created by government bureaucrats without any serious study, and that occurred more than 40 years ago,” Skrentny said. A better basis for anti-discrimination measures, he said, would be one based on the recognition of “a divide or hierarchy in America, of black and nonblack, with blacks on the bottom.”

John Hope Franklin of Duke University, the dean of U.S. black-history professors, a
gr
eed that this model makes sense. Black integration continues to move “at a snail’s pace,” he said, largely because most white Americans remain “stuck in their old ways.” Illinois’ Krysan, whose primary concern is black-white relations, agreed, citing continued segregation in public schools and housing.

Meanwhile, among richly integrated groups such as Native Americans, more than half of whom have intermarried, there’s uncertainty about what’s been gained by it.

Sharon Peregoy, 53, who lives on Montana’s Crow Reservation, for example, and has Puerto Rican, Asian and black in-laws, considers that a mixed blessing.

“Interracial dating is good, but it dilutes,” she said, in the sense that it’s left some of her grandnieces and nephews without enough Crow blood to qualify as tribal members.

“There’s a cultural shift and a language loss.”

Older and especially foreign-born generations of many Asian and Hispanic families share that concern, their Americanized offspring say.

Then there’s Sikkenga, an American of Dutch ancestry whose adopted son is black, who feels that he’s witnessed great social progress.

“Twenty years ago,” he said, “to have a black friend or couple over for dinner would have set the neighbors going.

“Now, most people don’t notice it anymore, and those who do are kind of ignorant.”